Scope: prerequisite step for Wave 3A's A3 assertion (displaySurface=monitor
verification). The page→offscreen bridge gains a new op so the harness can
query the active stream's `getSettings().displaySurface` without needing
direct offscreen.evaluate access (impossible by-construction; the only
cross-isolate path is chrome.runtime.sendMessage).
Bridge op contract (`src/test-hooks/offscreen-hooks.ts`):
- Protocol: { type: '__mokoshOffscreenQuery', op: 'get-display-surface' }
- Response: { displaySurface: string|null }
• null when no current stream (recording not active)
• 'monitor' when installFakeDisplayMedia's monkey-patched
getSettings() reports it (production code in
src/offscreen/recorder.ts enforces this same value — tears down
stream + throws 'wrong-display-surface' otherwise).
- Failure: { ok: false, error: <message> } only on getSettings throw.
Tier-1 grep gate extension (`tests/background/no-test-hooks-in-prod-bundle.test.ts`):
- FORBIDDEN_HOOK_STRINGS: 8 → 9 entries.
- Added: 'get-display-surface' (the literal bridge-op string;
matches the production-bundle absence invariant — the offscreen-hooks
module is tree-shaken in production builds by the Vite mode gate in
src/offscreen/recorder.ts top-of-module).
Verification:
- npx tsc: clean
- npm run build: clean (dist/ 4 chunks; no offscreen-hooks artifact)
- npm run build:test: clean (dist-test/ adds offscreen-hooks-DfWtG71P.js, 2.38kB)
- SKIP_BUILD=1 vitest run no-test-hooks-in-prod-bundle.test.ts → 10/10 GREEN
(1 build-sanity + 9 forbidden-string checks; production bundle hook-free)
- SKIP_BUILD=1 vitest run (full) → 93/93 GREEN
(Wave 0+1+2 baseline 92 + 1 from the 9th grep-gate string)
- npx tsx tests/uat/a6.test.ts → A6 5/5 GREEN
(lib-driven path preserved; bridge op addition does not interfere)
Wave 3A continuation: assertA1/A2/A3/A4 land in the next commit which
wires the harness-page surface + driver wrappers + harness.test.ts
orchestrator. This commit is the bridge prerequisite — keeping the
bridge-op extension atomic + the grep-gate extension atomic so the
'production bundle hook-free' invariant is provable BEFORE the page-side
surface lands.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Mark
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